Abstract: A signal transmission/reception device of an air conditioner is provided with a plurality of control groups (8A, 8B, . . . ). The control groups (8A, 8B, . . . ) are each composed so that an outdoor control unit (5) and an indoor control unit (6) are connected to each other through a group communication path (7) so as to be capable of signal transmission and reception therebetween. The outdoor control units (5,5, . . . ) are connected to each other through a centralized communication path (10) so as to be capable of signal transmission and reception among them. The respective group communication paths (7) are connected at the respective outdoor control units (5,5, . . . ) to the centralized communication path (10) thereby forming a single signal transmission/reception network (NW). Further, the signal transmission/reception network (NW) is connected to a centralized controller (9) for subjecting the outdoor units (3,3, . . . ) and the indoor units (4,4, . . . ) to centralized control.

Abstract: An ON-OFF controller (5B) connected to a plurality of indoor units (3, 3, . . . ) specifies a range of address settings of each of the indoor units (3, 3, . . . ) managed by the ON-OFF controller (5B), and outputs a signal showing the range of address settings to the respective indoor units (3, 3, . . . ) based on the range of address settings. When receiving the signal showing the range of address settings from the ON-OFF controller (5B), each of the indoor units (3, 3, . . . ) outputs to a remote control (4) a signal allowing an address setting, and stores an address for itself inputted from the remote control (4). The remote control (4) indicates the range of address settings when receiving the signal allowing an address setting from the indoor unit (3, 3, . . . ), and has an input button (4c) by which an address of the indoor unit (3, 3, . . . ) is inputted.

Abstract: A transmission device is disclosed wherein a plurality of control units each having a transmitting/receiving block connected to one another through a positive signal line and a negative signal line, and bidirectional signal transmission is carried out with a predetermined polarity among the control units. The signal lines of the transmission device are connected to a power superposing source for applying a predetermined DC voltage to the signal lines and each of the control units include a signal switch connected to the transmitting/receiving block for inverting and switching a transmission signal sent or received by the transmitting/receiving block, and a polarity judging device adapted to supply a homopolar signal when the potential of the positive signal line is higher than the potential of the negative signal line, and adapted to supply a heteropolar signal when the potential of the positive signal line is lower than the potential of the negative signal line.

Abstract: An air condition control unit is provided with an EEPROM previously memorizing respectively different specific numbers of indoor control units and power supply means. Further provided thereto are power supply judging means for judging whether a remote controller receives the power from another indoor control unit by monitoring power source lines, and power not-supply determining means for determining the unit of its own to be a unit which does not supply the power to the remote controller when the power supply judging means judges the remote controller receives the power.